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81 lines
2.4 KiB
81 lines
2.4 KiB
4 months ago
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/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* This optimization recognizes the common diamond selection pattern and
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* replaces it with an instance of the HSelect instruction.
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*
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* Recognized patterns:
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*
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* If [ Condition ]
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* / \
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* false branch true branch
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* \ /
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* Phi [FalseValue, TrueValue]
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*
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* and
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*
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* If [ Condition ]
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* / \
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* false branch true branch
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* return FalseValue return TrueValue
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*
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* The pattern will be simplified if `true_branch` and `false_branch` each
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* contain at most one instruction without any side effects.
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*
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* Blocks are merged into one and Select replaces the If and the Phi.
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*
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* For the first pattern it simplifies to:
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*
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* true branch
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* false branch
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* Select [FalseValue, TrueValue, Condition]
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*
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* For the second pattern it simplifies to:
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*
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* true branch
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* false branch
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* return Select [FalseValue, TrueValue, Condition]
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*
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* Note: In order to recognize no side-effect blocks, this optimization must be
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* run after the instruction simplifier has removed redundant suspend checks.
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*/
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#ifndef ART_COMPILER_OPTIMIZING_SELECT_GENERATOR_H_
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#define ART_COMPILER_OPTIMIZING_SELECT_GENERATOR_H_
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#include "optimization.h"
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namespace art {
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class HSelectGenerator : public HOptimization {
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public:
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HSelectGenerator(HGraph* graph,
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OptimizingCompilerStats* stats,
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const char* name = kSelectGeneratorPassName);
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bool Run() override;
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static constexpr const char* kSelectGeneratorPassName = "select_generator";
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private:
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DISALLOW_COPY_AND_ASSIGN(HSelectGenerator);
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};
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} // namespace art
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#endif // ART_COMPILER_OPTIMIZING_SELECT_GENERATOR_H_
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